Indofluorides in the AMF3-InF3 systems (A = K, Rb, Cs and M = Mg, zn) and optical properties of Cr3+:K0.38Mg0.38In0.62F3

Abstract Among the fluorides disclosed in the AMF 3 –InF 3 systems (A=K, Rb, Cs/M=Mg, Zn), the most favorable material for optical applications in relation with the optical quality of its crystals is K 0.38 Mg 0.38 In 0.62 F 3 (KMI), a distorted monoclinic Magneli-bronze, which crystals are grown from the melt. Cr 3+ introduced in this host is optically characterized by optical spectroscopy. The chromium ions in the single crystals occupy simultaneously centrosymmetric and non-centrosymmetric sites. The broad emission band ( 4 T 2 g → 4 A 2 g transition) obtained in the near infrared range is characteristic of a small crystal field effect (Dq=1476 cm −1 ). Crystal field analysis leads to a very good agreement between calculated and experimentally observed energy levels. Furthermore, dips observed in the absorption at about 15370 cm −1 are related to the calculated mixing between the wave functions, connected with the 4 T 2 g ( 4 F) and 2 E g ( 2 G) and 2 T 1 g ( 2 G) electronic levels.